On Monday 09 October 2017 04:50:18 pm E. Liddell wrote:
> On Mon, 9 Oct 2017 21:43:47 +0200
>
> Gerhard Zintel <gerhard.zintel@...> wrote:
> > On Monday 09 October 2017, Dr. Nikolaus Klepp wrote:
> > > When I start kmail without "starttde" - from xterm under fvwm for
> > > example - then klicking on a *.pdf in kmail results in a dialog popping
> > > up ("What application ..."). "kcontrol" starts with an empty
> > > splitscreen window, no modules visible.
> >
> > Same for me starting TDE applications. Not only Kmail asks for the kind
> > of program to be used to open any application. Even Konqueror asks for it
> > when adviced to open something in an external window. It opens PDF, PNG
> > and others fine in its internal viewer though.
>
> It sounds to me like KMail etc. are failing to find a list of associations
> between mimetypes and applications, but I'm not sure where that information
> is stored (I do seem to remember than KDE3 did not follow the standard for
> storing that information that's now used by most desktops--did we ever
> update
>
> E. Liddell
>

My issue is different but what I have found that might be relevant: 
https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html

When TDE starts up normal as the default DE,  lots of "declare -x XDG_=*"   
Trinity "stuff" gets set. Check your export command and compare the 
difference for a TDE session and a FVWM session.

greg